Device and method for applying coating material

ABSTRACT

In a device for depositing coating material with the manufacture of coated and/or impregnated sheet formations the thickness of the coated sheet formation is monitored with two metering rollers ( 11, 13 ) rotating against the sheet formation. The distance measurement between the contact surfaces ( 12, 14 ) of the metering rollers ( 11, 13 ) is carried out by way of measuring surfaces ( 16, 18 ) concentric to the metering rollers ( 11, 3 ) which have a smaller diameter (d 1 ) than the contact surfaces ( 12, 14 ).

[0001] The invention relates to a method and to a device for depositingcoating material with the manufacture of coated and/or impregnated sheetformations.

[0002] There are known a multitude of methods and devices which are usedfor the manufacture of coated and/or impregnated sheet formations.

[0003] With this for example substrates of various materals, such asplastic, sheet metal or fibre-glass may be coated. With fibre sheetformations such as e.g. tissues, fleece and weavings such methods arenot only used for coating but also for strengthening and filling thefibre sheet formation.

[0004] For coating, one-component as well as two-component systems ormixtures may be provided which in a fluid state may for example bedeposited onto the substrate by extrusion or brushing. A particularlyknown application of such a method lies in the coating of fibre sheetformations for manufacturing so-called “prepegs” in printed circuitboardmanufacture.

[0005] With this there exists high demands on the accuracy. Thethickness of the coated and/or impregnated sheet formation must remainwithin very small tolerance regions. Coated sheet formations typicallyhave a thickness of the size order of tenths of millimetres—thetolerances range within the micrometre region.

[0006] It has therefore already been suggested (see e.g.non-prepublished PCT application PCT/CH/00513) after the depositing ofthe coating material to provide an adjustable dimensioning gap which isformed by rollers running against the material web.

[0007] It has however been ascertained that with this known method thedemanded tolerances may no longer be achieved without further ado. Inparticular a sufficiently large centricity of roller surface and shaftmay not be achieved. A certain out-of-centre running of the rollers maytherefore not be avoided.

[0008] It is therefore the object of the present invention to avoid thedisadvantages of that which is known, in particular thus to provide adevice and a method for depositing coating material, with which themanufacture of coated and/or impregnated sheet formations is possiblewith the highest accuracy.

[0009] According to the invention this object is achieved with a deviceand with a method with the features of the characterising part of theindependent patent claims.

[0010] The device according to the invention for depositing coatingmaterial with the manufacture of coated and/or impregnated sheetformations comprises one or more depositing devices known per se fordepositing the coating onto the sheet formations. In the runningdirection, after the depositing device there is provided a dimensioninggap for dimensioning the thickness of the coated and/or impregnatedsheet formation movable through the gap. The width of the dimensioninggap is predeterminable so that the thickness of the coated and/orimpregnated sheet formation may be adjusted. The dimensioning gap islimited by at least one metering roller pressable with a contact surfaceagainst the sheet formation, and a counter-contact surface. To themetering roller and the counter-contact surface there is in each caseallocated a measuring surface. The distance of the measuring surfaces islarger than the dimensioning gap. This permits measuring sensors to beplaced between the measuring surfaces, which have no space in thedimensioning gap. In particular the at least one metering roller in theaxis direction at at least one end is provided with a cylindricalmeasuring surface. The cylindrical measuring surface has a smallerdiameter than the contact surface of the roller. The device furthermorecomprises a measuring arrangement which serves for measuring thedistance between the measuring surface and the reference measuringsurface which is defined in relation to the counter-contact surface.With the manufacturing procedure of the metering roller and thecounter-contact surface the measuring surfaces are formed in an exactlydefined position to the contact surfaces.

[0011] With the additionally provided measuring surface or surfaces thewidth of the dimensioning gap may be indirectly very preciselydetermined. Since the cylindrical measuring surface has a smallerdiameter than the contact surface of the roller the distance between themeasuring surface and the reference measuring surface with a measuringsensor lying therebetween may be measured without problem. Any occuringout-of-centre running between the bearing of the roller and the contactsurface of the roller is correctable on account of the measurement ofthe distance between the measuring surfaces since the measuring surfacesare arranged in an exactly defined relation to the contact surface.

[0012] It would however also be conceivable to permit eccentricitiesbetween the contact surface and the measuring surface, to determine witha refernece measurement and thereafter to compensate by calculation.

[0013] According to a particularly preferred embodiment example thecounter-contact surface is formed as a second roller. The referencemeasuring surface is formed as a second cylindrical measuring surfacewhich is arranged at at least one end of the second roller is the axisdirection and which has a smaller diameter than the contact surface ofthe second roller. The second measuring surface is likewise arrangedsymmetrically and concentrically to the contact surface of the secondroller. By way of the fact that the distance between the twocylindrical, concentric measuring surfaces arranged at a known distanceto the contact surfaces is measured, indirectly the width of thedimensioning gap may be very accurately determined.

[0014] Advantageously the two rollers rotate in the opposite directionto the movement direction of the sheet formation. According to aparticularly preferred embodiment example the cylindrical measuringsurface or surfaces have a diameter which correspond to more than 50%,advantageously about 70% of the diameter of the contact surface or ofthe contact surfaces of the roller or rollers. The diameter of themeasuring surface is to be selected as large as possible. The closer themeasuring surfaces lies to the contact surface the better eccentricitiesmay be avoided since the (smaller) distance between the measuringsurface and the contact surface may be more precisely controllable. Themeasuring surface may however not have the same diameter as the contactsurface. In this case the measuring surfaces would lie so close to oneanother that no sensors may be positioned therebetween. Furthermorethere would exist the danger of contamination of the measuring surfaceby the coating material doctored off with the roller.

[0015] According to a further preferred embodiment example the rollersare rotatably mounted such that the bearing of the one roller is fixedand that the bearing of the other roller with respect to the firstroller is displaceable perpendicular to the movement direction of thesheet formation. The thickness of the dimensioning gap may be adjustedby displacing the second roller towards the first roller or away fromthis.

[0016] According to a preferred embodiment example the two rollers arepressed together with a predermined force by pneumatics. Thedisplaceable roller for compensating the out-of-centre running ispressable outwards or displaceable inwards, against or with the force ofthe pneumatics, in particular with a piezoelectric element. Theapplication of a piezoelectric element permits in a particularly simplemanner a precise adjusting of the thickness of the dimensioning gap independence on the measured distance between the measuring surfaces. Withsuch an arrangement the thickness of the dimensioning gap may also besimply controlled (indirectly via the control of the distance betweenthe measuring surfaces). The device may furthermore be provided with anadjusting arrangement for adjusting the gap width. With this it isadditionally conceivable to measure the thickness of the coated sheetformation and to control via the adjusting arrangement. The adjustmentof the gap width with the piezoelectric element serves for compensatingan out-of-centre running, the adjusting arrangement serves for thecontrol of the thickness as a whole.

[0017] Advantageously furthermore between the contact surface and themeasuring surface there may be arranged an undercut. The undercut avoidsa contamination of the measuring surface by coating material doctoredfrom the sheet formation with the contact surface.

[0018] The roller or the rollers are furthermore in the known mannerprovided with a doctor blade with which coating material adhering to thecontact surface is removed and advantageously led again to thedepositing device.

[0019] The measuring arrangement consists advantageously of acontactless sensor, for example of an eddy current sensor. Also othersensors, e.g. optical ones would be conceivable.

[0020] The method according to the invention for manufacturing coatedand/or impregnated sheet formations may be particularly simply carriedout with a device of the described type. The coated and/or impregnatedsheet formation is led through an adjustable dimensioning gap betweentwo contact surfaces. According to the invention the distance betweenmeasuring surfaces which are defined in relation to the contact surfacesand lie at a greater distance to one another than the contact surfacesare measured. In particular the distance between one measuring surfacewith a smaller diameter than the cylindrical contact surface and areference measuring surface defined in relation to the second contactsurface is measured. Proceeding with the result of this measurement thewidth of the dimensioning gap is adjusted, prefereably controlled. Theinvention is thus to the first degree based on providing additionalmeasuring surfaces whose mutual distance may be freely selected withoutlimitation on account of the metering roller design.

[0021] The invention is hereinafter explained in more detail inembodiment examples and by way of the drawings. There are shown in:

[0022]FIG. 1 a schematic representation of a device according to theinvention,

[0023]FIG. 2 a schematic representation of the mounting of two contactrollers of a device according to the invention and

[0024]FIG. 3 a schematic representation of an alternative embodimentexample.

[0025] In FIG. 1 there is schematically shown a device 1 which servesfor manufacturing a coated or impregnated sheet formation F. The sheetformation F is typically a material web, e.g. a fibreglass tissue. Thesheet formation F in a movement direction R is firstly moistened in apre-moistening 2 and subsequently in an impregnating station 3 providedwith coating material B. The thickness D of the coated sheet formationis checked in a metering device 6. The sheet formation F coated and/orimpregnated in this manner is subsequently led to a drier 5 where thecoating material B on the sheet formation F is cured.

[0026] The dryer 5, the impregnating station 3 and the pre-moistening 2are generally common components and therefore will not be gone into indetail here.

[0027] The metering device 6 comprises in a known manner two meteringrollers 11, 13. The metering rollers 11, 13 form contact surfaces 12, 14for the coated sheet formation F. Between the contact surfaces 12, 14there is formed a dimensioning gap 10. The width a (see FIG. 2) of thedimensioning gap 10 defines the thickness D of the coated/impregnatedsheet formation F.

[0028] The sheet formation F in the vertical direction is led betweenthe metering rollers 11, 13. The metering rollers 11, 13 rotate oppositeto the movement direction R of the sheet formation. Typically themetering rollers 11, 13 rotate at about 4 revolutions per minute, whichcorresponds to about 3 metres per minute. By way of the contact of thecoated sheet formation F with the contact surface 12, 14, excess coatingmaterial B on the sheet formation is removed from this. By way of adoctor blade 4 the coating material adhering to the contact surface 12,14 of the metering rollers 11, 13 is doctored off.

[0029] The one metering roller 11 is in one direction E displaceableperpedicular to the sheet formation F towards the other metering roller13. By way of this the width a of the dimensioning gap 10 may beadjusted. The second metering roller 13 is fixedly mounted.

[0030] The width a of the dimensioning gap 10 with typical applicationsis about 0.3 mm. For this reason it is not possible to directly measurethe distance between the contact surfaces 12, 14.

[0031] Thus at least one of the metering rollers 11, 13, preferably bothmetering rollers 11, 13 are provided with a measuring surface 16, 18.The measuring surfaces 16, 18 are arranged in the axis direction A atboth ends 15 of the metering rollers 11, 13. The measuring surfaces 1618 run concentrically to the contact surfaces 12, 14. The meteringrollers 11, 13 are manufactured as turned parts wherein with themachining of the measuring surfaces 16, 18 the contact surfaces 12, 14serve as a reference. Even with any occuring out-of-centre running ofthe metering rollers 11, 13 there exists an exactly defined relationbetween the measuring surfaces 16, 18 and the corresponding contactsurfaces 12, 14.

[0032] The device 1 is furthermore provided with measuring sensors 17which measure the distance between the measuring surfaces 16, 18. Themeasuring sensors 17 are typically contactless sensors, e.g. eddycurrent sensors of the manufacturer Vibrometer SA.

[0033] In FIG. 2 the mounting of both metering rollers 11, 13 is shownenlarged. A first metering roller 13 with a contact surface 14 isfixedly mounted in a bearing 19. The diameter of the measuring surface18 is smaller than the diameter of the shaft of the metering roller.

[0034] The second metering roller 11 with the contact surface 12 is in abearing shell 20 on a linear guide 26, displaceably mounted in adirection E perpendicular to the sheet formation F towards the firstmetering roller 13. The bearing shell 20 for the metering roller 11 iswith a pneumatic cylinder 21 tensioned against a piezoelectric element23. The piezoelectric element 23 is supported on a double wedge 22 whichis displaceable by way of a threaded spindle 25 and a motor M.

[0035] For adjusting a dimensioning gap 10 to the desired gap width a,firstly the gap a is set to the desired value by displacing the doublewedge 22. This value is typically 0.3 mm. The two eddy current sensors17 are arranged between the measuring surfaces 16, 18 which are at adistance b to one another. The measuring sensors 17 are typicallypositioned 0.1 and 0.2 mm away from the measuring surface 16 and 18respectively. In operation the measuring sensors 17 continuously measurethe distance to the respective measuring surface 16 or 18. From this thedistance b between the measuring surfaces 16, 18 may be determined. Onaccount of the exactly defined relation between the measuring surfaces16, 18 and the contact surfaces 12, 14 a change in the distance bbetween the measuring surfaces 16, 18 on account of an out-of-centrerunning corresponds to the change of the gap width a between the contactsurfaces 12, 14. A precise monitoring is thus possible since themeasuring surfaces precisely e.g. 16, 18 proceeding from the contactsurfaces 12, 14 are formed as a reference.

[0036] The distance b between the measuring surfaces 16, 18 iscontrolled via the measuring sensors 17. A voltage dependent on thereading of the measuring sensors is applied to the piezoelectric element23. In the initial position the piezoeletric element 23 is typicallyimpinged with a voltage of 500 Volts. By variation of the voltagebetween 0 and 1,000 volts the metering roller 11 may be displaced inboth directions, by which means any occuring out-of-centre running ofthe metering rollers 11, 13 may be compensated. The distance b betweenthe measuring surfaces 18 and 16 is thus controlled via thepiezoelectric element 23 (input variable: the voltage at thepiezoelectric element). The control circuit is not shown in FIG. 2 forrepresentational reasons.

[0037] The device according to the invention is in particular to beapplied with the impregnation of sheet formations withsolvent-containing resins. It is therefore important that all appliedelements are explosion-safe. As measuring sensors 17 therefore eddycurrent sensors (manufacturer Vibrometer) are used. The piezoelectricelement 23 is accommodated in a housing in an explosion-safe manner.

[0038] The pneumatic cylinder 21, the bearing shell 20, thepiezoelectric element 23, the double wedge 22 and the bearing 19 lie inone plane.

[0039] The diameter of the measuring surfaces 16, 18 are to be selectedas large as possible. In this manner as small as possible toleranceswith respect to the contact surfaces 12, 14 may be achieved. The contactsurfaces 12, 14 have a diameter d2. In a certain embodiment example thediameter d2 of the contact surfaces 12, 14 is 240 mm whilst the diameterd1 of the measuring surfaces 16, 18 is 170 mm. The diameter d1 is chosedjust so high that the measuring sensors 17 may still be positionedbetween the measuring surfaces 16, 18.

[0040] The differing diameters d1, d2 furthermore prevent thecontamination of the measuring surfaces 16, 18 by the coating material Badhering to the contact surfaces 12, 14.

[0041] The control of the gap width a is effected with a frequency ofabout 30 Herz.

[0042] In FIG. 3 there is schematically shown an alternative embodimentexample. According to this example it is also conceivable to onlyprovide the one metering roller 11 with a measuring surface 16 with asmaller diameter, whilst the measuring surface 28 on the other meteringroller 13 is formed as a continuation of the contact surface 14. Thisarrangement too permits the positioning of measuring sensors between thetwo metering rollers 11, 13. In the embodiment example in FIG. 3 thereis furthermore shown an undercut 24 between the measuring surface 16 andthe contact surface 12 of the one metering roller 11. The undercut 24prevents a spillage of coating material M from the contact surface 12onto the measuring surface 16. Likewise there is provided an undercut 24on the other metering roller 13 which separates the contact surface 14thereof from the measuring surface 28.

[0043] Preferably the measuring surfaces seen in the axis direction Aare arranged on both sides of the rollers 11, 13—likewise measuringsensors are also arranged on both sides. It is however also conceivablethe carry out the measurement only on one side. With certainapplications it is also conceivable to define the dimensioning gap onlyon one side with a rotatable roller whilst the sheet formation on theother side is led over a fixed counter-contact surface.

1. A device for depositing coating material (B) with the manufacture ofcoated and/or impregnated sheet formations (F), with at least onedepositing device (2, 3) for depositing the coating (B) onto the sheetformation (F), and with a dimensioning gap (10) for dimensioning thethickness (D) of the coated and/or impregnated sheet formation (F)movable through the gap (10), wherein the width (a) of the dimensioninggap (10) is predeterminable and wherein the dimensioning gap (10) isdefined by at least one metering roller (11) pressable with a contactsurface (12) against the sheet formation (F), and by a counter-contactsurface (14), characterised in that to the metering roller (11) and tothe contact surface (12) there is in each case allocated a measuringsurface (16, 18, 28) whose distance (b) to one another is larger thanthe gap width (a), that in particular the metering roller (11) in theaxis direction (A) at least at one end (15) is provided with acylindrical measuring surface (16) whose diameter (d1) is smaller thanthe diameter of the contact surface (12) of the metering roller (11) andthat the device (1) comprises a measuring arrangement (17) for measuringthe distance (b) between the measuring surface and a reference measuringsurface (18, 28) which is defined in relation to the counter-contactsurface (18, 19).
 2. A device according to claim 1, characterised inthat the counter-contact surface is formed as a second metering roller(13) and that the reference measuring surface is formed as a secondcylindrical measuring surface (18) whose diameter (d1) is smaller thanthe diameter (d2) of the second roller (13).
 3. A device according toclaim 2, characterised in that the metering rollers (11, 13) arerotatably mounted in the opposite direction to the movement direction(R) of the sheet formation (F).
 4. A device according to one of theclaims 1 to 3, characterised in that the cylindrical measuring surface(16) or the cylindrical measuring surfaces (16, 18) have a diameter (d1)which corresponds to more than 50%, preferably about 70% of the diameter(d2) of the contact surfaces (12, 14).
 5. A device according to claim 3,characterised in that the rollers (11, 13) are rotatably mounted,wherein the bearing (19) of the first roller (13) is fixed and whereinthe bearing (20) of the second metering roller (13) in relation to theother metering roller (13) is displaceable in a direction (E)perpendicular to the sheet formation (F) for compensating anout-of-centre running.
 6. A device according to claim 5, characterisedin that the one metering roller (11) with a pneumatic cylinder (21) ispressable with a predetermined force against the other metering roller(13) and that the gap width (a) of the dimensioning gap (10) isadjustable with an adjusting-arrangement (M, 22).
 7. A device accordingto claim 6, characterised in that for moving the metering rollers (11,13) with or against the force of the pneumatic cylinder (2) there isprovided a piezoelectric element (23).
 8. A device according to one ofthe claims 1 to 7, characterised in that on the metering roller (11, 13)between the contact surfaces (12, 14) and the measuring surfaces (16,18, 28) there is arranged at least one undercut (24).
 9. A deviceaccording to one of the claims 1 to 8, characterised in that themeasuring arrangement (17) comprises at least one contactless sensor, inparticular an eddy current sensor.
 10. A method for manufacturing coatedand/or impregnated sheet formations (F), in particular with a deviceaccording to one of the claims 1 to 9, wherein the coated and/orimpregnated sheet formation (F) is led through an adjustabledimensioning gap (10) between two contact surfaces (12, 14),characterised in that the distance (b) between a measuring surface (16)defined in relation to the one contact surface, in particular acylindrical measuring surface with a smaller radius (d1) than thecylindrical contact surface (12) and a reference measuring surface (18)defined in relation to the second contact surface (14) is measured andthat the width (a) of the dimensioning gap (10) is adjusted depending onthe result of the measurement.
 11. A method according to claim 10,characterised in that the distance between the measuring surface (16)and the reference measuring surface (18) is controlled.